There are 2 types of energy in the game, Mist Energy and Crystal Energy. Mist Energy is the one with the 100 limit, which regenerates itself over a 22 hour period. Crystal Energy can be bought for real money in the Three Rings store, or can be bought and sold for crowns in the in-game market. Buying Crystal Energy in the market is the key:

What you can potentially do is:

1. Run the Clockworks until your Mist Energy is depleted.
2. Take the money you made off of that, and buy 100 Crystal Energy from the market.
3. Run the Clockworks until *that* is depleted
4. Buy more Crystal Energy from the market
...

So if Crystal Energy (CE) is selling at 4900 crowns for 100 CE, then you'd have to make at least 4900 crowns from your 100 Mist Energy in order to get the process started. You probably won't be able to pull this off in Tier 1 just off the crowns dropped by monsters, but with the AH (Auction House) to sell the various materials that drop from them as well, it *may* be possible to be self-sustaining in T1.

Once you reach Tier 2, it gets easier, as the crown drops are better there, and T2 monsters are more likely to drop materials that bring a good price in the AH.

But one thing - this only works if you can run the Clockworks without dying very often. In T1, the energy cost to revive starts at 2 for the first revive, then 4, then 8, then 16, etc. In T2 it's much worse, starting at 5, then 10, then 20, etc. So if you're spending too much energy on the revives, you won't be able to make enough money to buy more CE when your current energy is depleted.

Also note that in order to buy/make better gear, you'll need to spend crowns and/or energy. So you need to not just make enough to be able to buy energy for another run, but enough beyond that to build up towards getting the better gear you'll need to get into the deeper tiers.

I wouldn't count on being to run continuously and still be able to afford equipment upgrades right from the start. If nothing else, you need to spend some time on learning how to play the game without dying (during the course of which you'll probably die quite regularly). But once you've developed enough skill, and have gotten some decent gear, the above method works quite well.